1. Field of the Invention
The present invention relates to method of truing a chamfering grindstone and a chamfering device, and particularly relates to method of truing a chamfering grindstone which chamfers wafers for a semiconductor device, an electronic component and the like, and a chamfering device.
2. Description of the Related Art
Metal or resin is mainly used as a binder for a grindstone for performing chamfering work on a wafer of silicone or the like that is a material of high fragility.
A metal-bond grindstone has the advantage of having high abrasive grain holding power, but it is difficult to accurately align the center of a grindstone and the center of a spindle when the grindstone is mounted to a spindle even if strict tolerance is established, and therefore the metal-bond grindstone has the disadvantage of causing runout in an outer periphery.
On the other hand, a resin-bond grindstone does not have high abrasive grain holding power, but has the advantage of being able to suppress the occurrence of runout by newly creating a groove on the grindstone (groove for chamfering work) by carrying out truing after the grindstone is attached to the spindle.
However, when the resin-bond grindstone is trued with a chamfering device, a truing mechanism is additionally needed, and there is the disadvantage that the entire chamfering device becomes large in size and complicated with the truing mechanism associated with the chamfering device.
There has been proposed the truing tool and the wafer chamfering device with the truing tool which can perform truing of the grindstone with a simple mechanism as the device for compensating such a disadvantage (see Japanese Patent Application Publication No. 11-347901).
In this truing tool and the wafer chamfering device with the truing tool, by using the truing tool in which the truing grindstone formed into a predetermined shape is fixed to an outer peripheral part of a base material formed into a disc-shape, this truing tool is mounted on the same axis as the wafer table, and the wafer table and the grindstone are rotated to be relatively closer to each other, whereby an outer peripheral part of the truing tool is brought into contact with the outer periphery of the grindstone to true the grindstone.
However, in the truing method described in Japanese Patent Application Publication No. 11-347901, the truing tool of which outer peripheral part is formed into a predetermined shape is mounted on the same axis as the wafer table, but when the truing tool is worn and deformation occurs, or when the chamfering shape of the wafer is changed, another new truing tool has to be mounted again.
Each time a new truing tool is mounted, the truing tool has to be centered with respect to the rotational axis, and thus skilled technicians spend tremendous time in replacing the truing tools.